Belt transfer device

ABSTRACT

An electrostatic toner image transfer device is provided in which separate photoconductive elements are brought into registration at a transfer station against registration pins. Transfer of the toner image from the photoconductive element to a receiver sheet is accomplished by means of a transfer device comprising spaced rollers having an endless belt extending therearound which includes alternating conductor and insulative segments and has means for supporting the receiver thereon. A first potential can be applied to one roller to assure intimate contact between the receiver and the photoconductive element and a second and greater potential of the same polarity may be applied to the second roller to cause transfer of the toner image from the photoconductive element to the receiver. As the transfer device is moved through the transfer station the receiver is brought into progressive line contact with the photoconductive element by the first roller followed by the second roller which causes image transfer from the photoconductive element to the receiver and separation of the receiver from the photoconductive element along a progressive line. The segmented belt supports the receiver stationarily against the photoconductive element and successively conducts the potential applied by the respective rollers to the receiver. A plurality of transfer stations can be provided so that a plurality of images can be transferred sequentially to a single receiver, if desired.

United States Patent Nelson [54] BELT TRANSFER DEVICE Raymond L. Nelson,Rochester, NY.

Eastman Kodak Company, Rochester, NY.

22 Filed: Dec. 16,1970

211 Appl.No.: 98,501

[72] Inventor:

[73] Assignee:

3,519,343 7/1970 McNair et al.... 355/4 3,520,603 7/1970 Gnage ..355/43,551,046 12/1970 Gnage ..355/4 Primary Examiner-Joseph F. Peters, Jr.Assistant Examiner-Robert P. Greiner AnomeyW. H. J. Kline and Gary D.Fields Feb. 22, 1972 [57] ABSTRACT An electrostatic toner image transferdevice is provided in which separate photoconductive elements arebrought into registration at a transfer station against registrationpins. Transfer of the toner image from the photoconductive element to areceiver sheet is accomplished by means of a transfer device comprisingspaced rollers having an endless belt extending therearound whichincludes alternating conductor and insulative segments and has means forsupporting the receiver thereon. A first potential can be applied to oneroller to assure intimate contact between the receiver and thephotoconductive element and a second and greater potential of the samepolarity may be applied to the second roller to cause transfer of thetoner image from the photoconductive element to the receiver. As thetransfer device is moved through the transfer station the receiver isbrought into progressive line contact with the photoconductive elementby the first roller followed by the second roller which causes imagetransfer from the photoconductive element to the receiver and separationof the receiver from the photoconductive element along a progressiveline. The segmented belt supports the receiver stationarily against thephotoconductive element and successively conducts the potential appliedby the respective rollers to the receiver. A plurality of transferstations can be provided so that a plurality of images can betransferred sequentially to a single receiver, if desired.

7 Claims, 2 Drawing Figures PAIENTEDFEB22 1912 3,544, 034

SHEET 1 0F 2 0 v RAYMOND L. NELSON INVENTOR. 1

BY WM ATTORNEYS PATENTEDFEBZZ I972 3, 44,0 4

SHEET 2 [IF 2 RAYMOND L. NELSON INVENTOR.

M fiwa Wu ATTORNEYS BELT TRANSFER DEVICE CROSS-REFERENCE TO RELATEDAPPLICATION The apparatus of this invention may be utilized in thedevice disclosed in commonly assigned U.S. Pat. application, Ser. No.741,359 to John S. Pollock, filed July I, 1968 and entitled PrintingApparatus."

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to a transfer device for transfer of an electrostatic tonerimage from the surface of a photoconductive element to a receiver, andmore particularly to such a device for transferring images wherein thereceiver is first brought into intimate contact with the photoconductiveelement by applicationof a first potential and then is transferred uponapplication ofa second potential.

Description of the Prior Art In a typical electrophotographic device, aphotoconductive element has a substantially uniform electrostatic chargeplaced thereon which is exposed to a pattern of radiation to form anelectrostatic image. This image is then developed by a developingmaterial containing toner particles, having a charge opposite theelectrostatic image charge, which are attracted to the electrostaticimage to form a toner image. Typically, this toner image may betransferred to a receiver by bringing the photoconductive element intointimate contact with the receiver and applying a potential to thereceiver which is opposite that of the electrostatic toner image so thatthe image is transferred to the receiver.

U.S. Pat. No. 3,328,193 to Oliphant et al. is directed to a transferdevice which includes a plurality of opposed rollers to which anincreasing potential is applied in the direction of movement of asuperimposed copy sheet and master to effect image transfer from themaster to the copy sheet.

SUMMARY OF THE INVENTION In accordance with this invention a transferdevice is provided which includes an endless belt having alternatingconductive and insulative segments and movable along an endless patharound first and second spaced conductive supports. Means is provided onthe belt for supporting a receiver across a plurality of the segments.The endless belt is movable along a transfer path past a surface bearinga toner image and is movable along the endless path so that a receiveron the belt is brought into intimate progressive line contact by thefirst conductive support to which a first potential is applied. Imagetransfer is obtained by the second conductive support to which a secondpotential is applied, followed by immediate separation of the receiverfrom the surface.

More particularly, a transfer device which is movable along a transferpath is provided with first and second spaced rollers having an endlesssegmented belt extending therearound which belt has alternatingconductive and insulative segments and including means for holding areceiver so that upon movement of the transfer device along the transferpath the first roller causes the receiver to be brought into intimateprogressive line contact with the photoconductive element and the secondroller causes image transfer of the toner image from the photoconductiveelement to the receiver followed by separation of the receiver from thephotoconductive element along a progressive line. The transfer devicecan be used for multiple image transfer in which the transfer devicemoves through a plurality of transfer stations to effect image transferfrom a plurality of photoconductive elements to form a composite print.

Additional novel features of this invention will become apparent fromthe description which follows.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary perspectiveview showing a carriage mechanism for transporting photoconductiveelements to separate transfer stations and a transfer device movablethrough the transfer stations to effect toner image transfer from eachphotoconductive element to a receiver on the transfer device; and

FIG. 2 is an enlarged perspective view of a portion of the transferdevice of FIG. 1 showing further details of its construction.

DESCRIPTION OF THE PREFERRED EMBODIMENT In an electrophotographic devicefor making a composite print from separate images, separatephotoconductive surfaces are charged and exposed to separate images,such as color separation images, to form corresponding electrostaticimages thereon. The photoconductive elements then pass throughdeveloping stations which tone the electrostatic images for subsequenttransfer to a single receiver in registry to make a composite print.

In accordance with this invention, a carriage transport mechanism C isprovided, having a plurality of carriages 2, 2' and 2" attached totiming belts 4, 4' and 4" respectively which are driven, as shown, by amotor 6 through endless belt 8. Each carriage supports a photoconductiveelement 10 and is moved across developing stations l2, l2 and 12",respectively to respective transfer stations where they are brought intoengagement with alignment means, such as registration pins 14.Advantageously, these pins are positioned to space the photoconductiveelements with equal distances between the reading edge of adjacentphotoconductive elements.

The transfer device T includes first and second spaced rollers l6 and 18rotatably mounted in a generally U-shaped frame or carriage 20. Anendless, segmented belt 22 extends around the rollers. Frame 20 isillustrated as being attached to a timing belt 24 driven by a motor 26through an endless belt 28, as shown. The rollers are caused to rotatein a counterclockwise direction, as viewed in FIG. 1, as the transferdevice is driven across the transfer station by means of a gear 30 onroller shaft 17 which engages a rack 32 and is sized so that endless,segmented belt 22 makes one revolution from the position where itengages the first photoconductive clement until the position where itengages the second photoconductive element as it moves along a transferpath past the transfer stations. Conveniently, each photoconductiveelement is connected to ground, as by a lead 34, whereas roller 16 isconnected to a first potential 36 and roller 18 is connected to asecond, but greater, potential 38 ofthe same polarity.

As best seen in FIG. 2, a receiver sheet 40 is attached to segmentedbelt 22, as by resilient clips 42 which engage opposite ends of thesheet. Alternatively, the receiver can be electrostatically tacked tothe segmented belt by means, not shown. Conveniently, the segmented beltincludes relatively wide conductive segments 44 interconnected byrelatively narrow segments 46. The belt can be made from a web of mylarwhich has a nickel coating on one side which coating is removed alongnarrow lines, such as one-sixteenth inch wide across the mylar belt andspaced approximately one-half inch apart. Thus, the bare mylar stripsform insulative segments 46 whereas the nickel-coated portions form theconductive segments 44. A conductive lacquer can be applied as a layeron the edges and underside of the belt as strips 48 to provide aconductive path between each segment and the respective rollers. Thesize and spacing of the segments can be varied provided that they arenot so wide as to reach from one roller to the other and preferably theinsulating segments are narrow in comparison to the conductive segmentsand there are at least two segments on each side of the belt between therollers. The receiver 40 must be sufficiently conductive that itelectrically bridges the space between conductive segments of the beltbut not so conductive that a significant current passes through it whenit is covering parts of both rollers at the same time. By way ofexample, a potential in the range of-lOO volts to 200 volts applied tothe first roller and a potential on the order of I,OO0 volts applied tothe second roller has been found to be satisfactory.

As transfer device T moves along the transfer path past thephotoconductive elements, the rollers revolve so that the receiver isbrought into progressive line contact with the upper surface ofsegmented belt 22 and is held stationary with 'respect to eachphotoconductive surface while in contact therewith. Thus, receiver 40 isfirst brought into contact with a photoconductive element by roller 16moving along the transfer path past the photoconductive element bearinga toner image. It remains in contact with the photoconductive elementuntil roller [8 moves therepast, at which time image transfer takesplace and receiver 40 is pulled away from photoconductive element 10along a progressive line. The significant feature of this sequence isthat as the paper is first brought into contact with photoconductiveelement 10, the potential between the receiver 40 and thephotoconductive element is chosen so that the charged marking particleswill not be repelled from the photoconductive element onto the receiverbut is strong enough to bring the receiver and photoconductive elementinto intimate contact. However, as roller 18 passes underneath receiver40, the potential between the paper and the photoconductive element 10is of sufficient potential to cause a transfer of toner particles fromthe photoconductive element 10 to receiver 40 to effect transfer of thetoner image.

From the foregoing, the advantages of this invention are readilyapparent. A transfer device has been provided which supports a receiversheet by means of a segmented endless belt so that it is brought intointimate progressive line contact with successive photoconductiveelements by a first roller to which a potential is applied, prior toimage transfer which is subsequently effected by a second roller towhich a second and greater potential is applied after which separationof the receiver from the photoconductive elements is effected along aprogessive line.

The invention has been described in detail with reference to a preferredembodiment thereof, but it will be understood that variations andmodifications can be effected within the spirit and scope of theinvention.

lclaim:

l. A transfer device movable along a transfer path for transferring atoner image from a surface to a receiver, said device comprising:

a first conductive endless belt support; I

a second conductive endless belt support spaced from said first support,said first and second supports being mounted for movement along saidtransfer path;

a movable endless belt cxtendable around said first and second supportsand having alternating conductive and insulative segments extendingthereacross and engageable with said supports;

means for holding the receiver on said segmented belt so that thereceiver is extendable across a plurality of said segments;

means for moving said endless belt along said transfer path past saidsurface and for moving said endless belt along said endless path tobring the receiver into progressive line contact with said surface toeffect transfer of said toner image from said surface to the receiverand to separate the receiver from said surface along a progressive lineafter transfer;

means for applying a first potential to said first support for bringingthe receiver into intimate progressive line contact with said surface assaid transfer device is moved thereacross; and

means for applying a second potential to said second support foreffecting image transfer of said toner image from said surface to thereceiver upon movement of said second support past said surface.

2. A transfer device movable along a transfer path for transferring atoner image from a photoconductive element onto a receiver supported bysaid transfer device, said device comprising: I

a transfer carriage movable along said transfer path;

a first roller rotatably mounted on said carriage;

a second roller spaced from said first roller and rotatably mounted onsaid transfer carriage; an endless belt extendable around said first andsecond rollers and having alternating conductive and insulative segments extending thereacross, said conductive segments being engageablewith said rollers and said belt being movable along an endless path;means for attaching the receiver to said segmented belt so that thereceiver is extendable across a plurality of said segments;

means for moving said transfer carriage along said transfer path pastsaid photoconductive element and for moving said endless belt along saidendless path to bring the receiver into progressive line contact withsaid photoconductive element to effect transfer of said toner image fromsaid photoconductive element to the receiver and to separate thereceiver from said photoconductive element along a progressive lineafter transfer;

means for applying a first potential to said first roller for bringingthe receiver into intimate progressive line contact with saidphotoconductive element as said transfer device is moved thereacross;and

means for applying a second potential to said second roller foreffecting image transfer of said toner image from said photoconductiveelement to the receiver upon movement ofsaid second roller past saidphotoconductive element.

3. A transfer device as claimed in claim 2, wherein:

said conductive segments are wider than said insulative segments.

4. A transfer device, as claimed in claim 2, wherein said'belt includes:

an endless web of insulative material having an outer surface whichincludes said insulative segments and having an inner surface;

a plurality of spaced conductive segments across said outer surface ofsaid web to form said conductive segments; and

a plurality of conductive strips in contact respectively with saidconductive segments and extending across said inner surface of said webto make electrical contact with said rollers, 5. A transfer device,'asclaimed in claim 2, wherein said moving means includes:

a shaft extending from one of said rollers; a pinion connected to saidshaft; a rack extending along said transfer path and engageable by saidpinion; and I a drive means connected to said carriage to move saidcarriage along said transfer path to cause said pinion to rotate saidone roller and said endless belt due to engagement ofsaid pinion withsaid rack.

6. An electrophotographic device for effecting transfer of a toner imagefrom at least one photoconductive element onto a receiver movable alonga transfer path, said device comprising: I

a first transfer station along said transfer path;

means for moving a first photoconductive element having a first tonerimage into said first transfer station;

means at said first transfer station for aligning said photoconductiveelement;

a transfer carriage movable along said transfer path;

a first roller rotatably mounted on said carriage;

a second roller spaced from said first roller and rotatably mounted onsaid transfer carriage;

an endless belt extendable around said first and second rollers andformed of alternating conductive and insulative segments extendingthereacross, said conductive segments being engageable with said rollersand said belt being movable along an endless path;

means for attaching the receiver to said segmented belt so that thereceiver is extendable across a plurality of said segments;

means for moving said transfer carriage along said transfer path pastsaid first photoconductive element and for moving said endless beltalong said endless path to bring the receiver into progressive linecontact with said first photoconductive element to effect transfer ofsaid first toner image from said first photoconductive element to thereceiver and to separate the receiver from said photoconductive elementalong a progressive line after transfer;

means for applying a first potential to said first roller for bringingthe receiver into intimate progressive line contact with said firstphotoconductive element as said transfer device is moved thereacross;and

means for applying a second potential to said second roller foreffecting image transfer of said first toner image from said firstphotoconductive element to the receiver upon movement of said secondroller past said first photoconductive element.

7. An electrophotographic device, as claimed in claim 6 5 furtherincluding:

1. A transfer device movable along a transfer path for transferring atoner image from a surface to a receiver, said device comprising: afirst conductive endless belt support; a second conductive endless beltsupport spaced from said first support, said first and second supportsbeing mounted for movement along said transfer path; a movable endlessbelt extendable around said first and second supports and havingalternating conductive and insulative segments extending thereacross andengageable with said supports; means for holding the receiver on saidsegmented belt so that the receiver is extendable across a plurality ofsaid segments; means for moving said endless belt along said transferpath past said surface and for moving said endless belt along saidendless path to bring the receiver into progressive line contact withsaid surface to effect transfer of said toner image from said surface tothe receiver and to separate the receiver from said surface along aprogressive line after transfer; means for applying a first potential tosaid first support for bringing the receiver into intimate progressiveline contact with said surface as said transfer device is movedthereacross; and means for applying a second potential to said secondsupport for effecting image transfer of said toner image from saidsurface to the receiver upon movement of said second support past saidsurface.
 2. A transfer device movable along a transfer path fortransferring a toner image from a photoconductive element onto areceiver supported by said transfer device, said device comprising: atransfer carriage movable along said transfer path; a first rollerrotatably mounted on said carriage; a second roller spaced from saidfirst roller and rotatably mounted on said transfer carriage; an endlessbelt extendable around said first and second rollers and havingalternating conductive and insulative segments extending thereacross,said conductive segments being engageable with said rollers and saidbelt being movable along an endless path; means for attaching thereceiver to said segmented belt so that the receiver is extendableacross a plurality of said segments; means for moving said transfercarriage along said transfer path past said photoconductive element andfor moving said endless belt along said endless path to bring thereceiver into progressive line contact with said photoconductive elementto effect transfer of said toner image from said photoconductive elementto the receiver and to separate the receiver from said photoconductiveelement along a progressive line after transfer; means for applying afirst potential to said first roller for bringing the receiver intointimate progressive line contact with said photoconductive element assaid transfer device is moved thereacross; and means for applying asecond potential to said second roller for effecting image transfer ofsaid toner image from said photoconductive element to the receiver uponmovement of said second roller past said photoconductive element.
 3. Atransfer device as claimed in claim 2, wherein: said conductive segmentsare wider than said insulative segments.
 4. A transfer device, asclaimed in claim 2, wherein said belt includes: an endless web ofinsulative material having an outer surface which includes saidinsulative segments and having an inner surface; a plurality of spacedconductive segments across said outer surface of said web to form saidconductive segments; and a plurality of conductive strips in contactrespectively with said conductive segments and extending across saidinner surface of said web to mAke electrical contact with said rollers.5. A transfer device, as claimed in claim 2, wherein said moving meansincludes: a shaft extending from one of said rollers; a pinion connectedto said shaft; a rack extending along said transfer path and engageableby said pinion; and a drive means connected to said carriage to movesaid carriage along said transfer path to cause said pinion to rotatesaid one roller and said endless belt due to engagement of said pinionwith said rack.
 6. An electrophotographic device for effecting transferof a toner image from at least one photoconductive element onto areceiver movable along a transfer path, said device comprising: a firsttransfer station along said transfer path; means for moving a firstphotoconductive element having a first toner image into said firsttransfer station; means at said first transfer station for aligning saidphotoconductive element; a transfer carriage movable along said transferpath; a first roller rotatably mounted on said carriage; a second rollerspaced from said first roller and rotatably mounted on said transfercarriage; an endless belt extendable around said first and secondrollers and formed of alternating conductive and insulative segmentsextending thereacross, said conductive segments being engageable withsaid rollers and said belt being movable along an endless path; meansfor attaching the receiver to said segmented belt so that the receiveris extendable across a plurality of said segments; means for moving saidtransfer carriage along said transfer path past said firstphotoconductive element and for moving said endless belt along saidendless path to bring the receiver into progressive line contact withsaid first photoconductive element to effect transfer of said firsttoner image from said first photoconductive element to the receiver andto separate the receiver from said photoconductive element along aprogressive line after transfer; means for applying a first potential tosaid first roller for bringing the receiver into intimate progressiveline contact with said first photoconductive element as said transferdevice is moved thereacross; and means for applying a second potentialto said second roller for effecting image transfer of said first tonerimage from said first photoconductive element to the receiver uponmovement of said second roller past said first photoconductive element.7. An electrophotographic device, as claimed in claim 6, furtherincluding: a second transfer station along said transfer path; secondmeans for moving a second photoconductive element having a second tonerimage into said second transfer station to effect transfer of saidsecond image to said receiver to form a composite image upon movement ofsaid transfer device along said transfer path past said second transferstation.